When tooth decay is noted, a dentist may remove the decay by drilling, cleaning out the cavity so formed in the tooth and then shaping the cavity to accept a filling material. The filling procedure has the purpose of sealing the cavity from its environment and also rebuilding the tooth to its previous shape and form. Conventional filling materials are e.g. amalgams, acrylate polymers and silicate compositions. A primary problem in filling cavities however, is sealing or bonding the filling material to the freshly exposed tooth surface. This surface is most usually the dentin layer of the tooth. If a filling is improperly sealed or bonded to the tooth surface, leakage will occur with the result that oral bacteria will enter the cavity area and eventually cause a decay under the filling. This results in the necessity of removing the filling and the new decay with the production of an even larger cavity which must then be filled.
Mercury amalgam filling materials have a tendency to corrode at the interface with the tooth, and the corrosion products form a seal with the tooth thereby significantly impeding the inflow of saliva and oral bacterial. These mercury containing corrosion products are themselves toxic, however, so this method of sealing is less than satisfactory. In addition, the amalgam fillings are excessively visible and do not match natural tooth colors.
Organic polymer filling materials, e.g. methacrylates and polymethacrylates, can be produced so that they form strong cavity filling materials. Also, these materials can be tinted so that they match the natural tooth color and become virtually indistinguishable from the natural tooth. In addition, these polymeric materials do not corrode and do not produce toxic products when they are present in the mouth. Unfortunately, these organic polymer filling materials do not bond strongly to the dentin tooth layer, thereby permitting secondary decay processes which result in the necessary cavity enlargement and refilling procedures as described above.
It would therefore be beneficial to provide compositions and a means for strongly and tightly sealing the tooth surface of a cavity to the preferrable organic polymer filling materials known in the art.
The present invention provides certain substances which may be utilized to strongly and tightly seal organic polymeric filling materials to the dentin tooth layer. The substances of the invention comprise sites which readily combine with dentin to produce strong covalent bonds. These substances also beneficially comprise an additional site which may be utilized to copolymerize with the known organic polymer filling materials. Thus, the organic polymer cavity filling materials essentially become chemically bonded to the dentin through the intermediacy of the novel substances of the invention. Other compositions are known in the art for bonding organic polymer filling materials to the exposed cavity surface; however, the present compositions have demonstrated superior bonding strengths when compared to the known compositions. Further details of this improved property are given below.